CORROSION The University of Technology Brno, School of chemistry Pavel Haška

Something about corrosion When was rust define? In 30th years 20th century. What´s heart of corrosion? Physical-chemical destruction of materials by ambient enviroment. How is corrosion defined? Spontaneous non-reversible proceed sequential erosion of materials by physical-chemical ambient enviroment. What corrode the rust? just about all materials, not only metals and their alloy, but non- metal materials, as ceramic and silicated anorganic matter (glass, concrete), or organic matter (rubber, plastic materials) and other materials How influence the corrosion? 3 basic factors: material, corrosion rate, medium of corrosion

Metal corrosion When rust proceed ? energy primary component of sys corrostion is higher as energy product of corrosion Just about all metals are unstable from thermodynamic view, mainly technical metals. How corrosion show ? loss of material and creation corrosive products, material changes (loss of strength and ductulity, birth of microcrack). Some changes are showed, when time expiry.

Type of corrosion Uniform corrosion Nonuniform corrosion Stain corrosion Pitting corrosion Point corrosion Undersurface corrosion Selective corrosion Intergranular corrosion Transgranular corrosion Extraction corrosion Crack of corrosion

UNIFORM CORROSION NONUNIFORM CORROSION STAIN CORROSION PITTING CORROSION POINT CORROSION UNDERSURFACE CORROSION SELECTIVE CORROSION INTERGRANULAR CORROSION TRANSGRANULAR CORROSION EXTRACTION CORROSION CRACK OF CORROSION

Rust protection Form corroding medium Choice of available material Model solution Manufacturing technology Electrochemical cover Surface treatment

katodic protect (e.g. zinc coatings in steel) we can enrich surface of metal by alloying elements (e.g. hot chromizing, alumining) coating isolate protect surface against corrosion medium (e.g. corrosion protective paint and plastics, coatings from tin in steel) synthetic compound layer of protect metal has better protective properties (e.g. phosphated coatings in steel, oxidized coatings in aluminium) layer of matter has inhibic effect for protective metal (e.g. chromate treatment of zinc, inhibic basic paint)

In conclusion Metals are used in all world for many years. Plastic materials are substituted step by step, but the metals play always perform in models and other branches, we can used in common life. Some metal are recyclable. They are used, because are economic favourable. Protect of steel is still evolvic branch. „Every day“ create new techniques for protect against corrosion.

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